It is generally known that a person carrying loads on his or her back—especially if such transports are frequent and/or prolonged and if the loads are moreover heavy and/or relatively large—is liable, at least in the long term, to more or less serious back problems or even to irreversible injuries. Therefore, on one hand, suitcases including a device comprising at least one roller and a handle or a similar means, and on the other hand (in the field in which the present invention is more particularly situated), devices for transporting loads that are more specifically conceived for hikers have appeared on the market, whose common goal it is to relieve one's back through a substantial reduction of the effort required for the transport of the aforesaid loads and to make especially hikers unaware of the strain of carrying a burden.
The main problem of this kind of transport devices is in the comfort and the ease of use. This essential requirement implies that the transport device should be simple and light in construction and quick and easy to assemble and disassemble, all without compromising its reliability. In addition, its selling price should remain affordable, which requires a rational and inexpensive manufacture, while the materials of its components should be of high quality. The problem is therefore all the more difficult to solve as it appears polymorphous in the sense that it includes a series of components constituting each a subproblem, and a partial solution of a subproblem may be a hindrance for a partial solution of another component of the problem. Thus, for example, it is apparent that the lighter the frame, the easier the device will be to handle, to carry and to pull. Yet, on the other hand, it is important for the frame to be stable and rigid. However, while a reinforcement of the frame particularly serves the aim of increasing the stability and rigidity, it results in an increase in weight, whereas the selection of certain light materials confronts the manufacturer with costs that may rapidly become prohibitive. In analysis, these antagonisms are subordinated to a condition sine qua non for a high comfort in use, namely that of the equilibrium and the stability of the device when it is being pulled or maneuvered in any other way. It is therefore fundamental to provide an optimal equilibrium (the stability being indeed a result of the latter).
Ultimately, the user wants a device of this kind to be as polyvalent as possible, i.e. applicable both in difficult terrain (more or less steep trails and paths that are hardly or not passable for cars) and in flat or paved terrain (suburbs, train stations etc.).
It is easily understood that the problem arising with respect to the attaching device that the user may employ for pulling or pushing the transport device is quite analogous to what has been said in regard of the latter. In fact, on the ergonomic level, firstly, a comfortable use of the attaching device must be ensured, and care must be taken to relieve the back through a substantial reduction and an ideal distribution of the efforts furnished in the transport of a load. Secondly, according to a more technical aspect, the attaching device must be designed such that its application is practical and rational. Ultimately, a third aspect consists in combining the esthetic aspect with the two others, the ergonomic and the technical aspect, rather than sacrificing it to them.
Different kinds of devices for transporting burdens are currently available, as well as different attaching devices ranging from a simple belt to a complex harness.
French patent application FR-A-2,775,878 discloses a transport device and an attaching device. The transport device is in the form of a frame composed of two longitudinal laths extending symmetrically with respect to a median plane, of one or a plurality of reinforcing cross members and of a supporting brace. The lower ends are brought nearer together to another in order to be spaced apart only a small distance and are interconnected by a device providing support on the ground, e.g. a shaft provided with a wheel, and whose plane coincides with the mentioned median plane. These laths separate toward their upper ends, each of which comprises a supporting piece intended to rest on the hips of the carrier, the two pieces being connected to each other by a belt.
The load, placed on the supporting brace, is provided with shoulder straps passing over the shoulders of the carrier. The latter are thus relieved of a large part of the load's weight, the latter being distributed on the wheel and on the hips. However, the advantage is counteracted by a substantial drawback, since the hips will be continuously subject to a double stress in the vertical (part of the load's weight resting on the hips) and lateral directions (caused by pitching the device). A reduction of one of the two stresses as a result of shifting the load in a horizontal plane, i.e. of a modification of the location of the supporting brace, will cause a corresponding increase of the other stress.
The applications of these transport and attaching devices are extremely limited, and the rigidity particularly of the transport device appears to be rather mediocre and, most importantly, its stability and equilibrium are not ensured for the reasons exposed below.
U.S. Pat. No. 4,664,395 discloses a device for transporting a load comprising a carriage or support chassis and a harness. The chassis is formed of two longitudinal bars and of a plurality of cross members and is provided with a pair of foldable legs. The bars converge at their lower ends, near which a wheel equipped with brakes is arranged. As to the harness, it is composed of a lower and upper belt, disposed around the waist and the chest, respectively, and a pair of suspenders, on one hand, and on the other hand, of a dorsal structure formed of two tubes. The harness further comprises specifically a holster or more generally an attachment for receiving a brake handle similar to that of a bicycle, the handle being connected to the wheel or more precisely to a slottet jaw for a brake linings via a cable passing over the user's shoulder. Connected to this dorsal structure are the two aforementioned belts, on one hand, and on the other hand, in its upper area, the upper ends of the chassis of the transport device.
Particularly the harness is quite complex and heavy, and therefore clumsy but also unaesthetic, and wearing it seems at the least awkward as it rather resembles a pillory, such that the user will rapidly abandon it and thus the entire transport device. Also, the very conception of the latter is such that both its equilibrium in use and its rigidity are insufficient.
These two references have at least one characteristic in common—which accounts at least partially for the lack of stability and of equilibrium of the devices disclosed therein—namely the fact that the laths or bars respectively of the chassis, possibly connected to each other by at least one cross member, extend on either side of a median plane to converge at their lower ends, between which the member for providing support on the ground is mounted. Moreover, the transport device and attaching device are rigidly connected to each other.
Thus, the exposed problem, or rather the array of problems set forth above remains unsolved, both with regard to the transport device and the attaching device.